Computer users form queries to determine which documents (i.e., files or objects) maintained in a file system have properties that match one or more properties provided in the query. For expedience, the user typically desires the results of the query to be sorted in some fashion by the query engine, particularly when querying across a large set of documents. If the results of the query comprise a large result set, the sorting process may take a substantial amount of time.
Two conventional types of querying programs may be run. A first type of querying program walks through a set of files by individually opening each file and extracting properties therefrom. If the properties of a given file match the criteria set forth in the query, that file is included in the result set. Although this type of program ultimately locates the matching files, this method is an extremely time consuming process, particularly when dealing with a substantial number of files. If it is desired that the result set be sorted, the process is even lengthier unless the documents are tested in an order that coincidentally matches the sort order (e.g., in alphabetical order).
A second type of querying program runs as a user-level program that accesses a database of properties maintained for a set of documents. Such a database is only updated upon user command, and thus the user must remember to continually update it each time a document is modified otherwise the database will be out of date. Accordingly, this type of querying program works well with a set of documents that is ordinarily static. However, this type of querying program is often unreliable or unworkable with a set of documents that is dynamic, since it is a time consuming, labor intensive and error prone process to continually keep the database current when dealing with changing documents. The problems are particularly evident when multiple users modify the documents, since each such user must be trained to run (and remember to run) the database updating program each time that a user modifies a document. Moreover, like a traditional database, with such conventional database programs the presentation of the result set is limited according to how the database is structured when it is created.